1. Field of Invention
The invention relates generally to computer systems. More particularly, methods and apparatus for decoding images in a browser environment are disclosed.
2. Description of Relevant Art
The explosive growth in Internet traffic has made it critical to look for ways of accommodating the increasing number of users while preventing excessive delays, congestion and widespread blackouts. For the past several years a large proportion of Internet traffic has been generated by web-browsing and most of the web browsing traffic is in turn comprised of digital images. This trend will continue with more sites becoming media rich as the users"" access bandwidths increase and media-enabled PCs become more common.
This great increase in the number and size of digital images being transmitted over the Internet and subsequently stored in both personal as well as host computers has led to a great deal of effort being devoted to studying image coding and decoding techniques. Such techniques are useful in both preserving memory resources but also improves system performance by reducing the amount of data required to be processed and transmitted over various networks.
Several conventional techniques are used to both encode and subsequently decode digital images that will ultimately be output to a computer display. In computer display technology, a color is set for each individual pixel or addressable illumination element on the screen. Each pixel has a red, a green, and a blue (RGB) component. By specifying the amount of intensity for each of these components, a distinct color is given to that pixel. Therefore, each pixel has associated with it a specific number of bits corresponding to the number of red, green, and blue color components used to derive what is referred to as a color-palette, or number of available colors. By way of example, for Web presentations, available color pallets are limited to the 256 colors represented by an 8-bit variation for each pixel that most computer monitors can display. Occasionally, users with very high-quality display monitors and adapters that provides a 24-bit variation for each pixel can view up to 16,777,216 different colors. However, since most computers can only handle an 8-bit variation, limiting the display to a 256 color-palette, digital images with 24-bit color resolution have substantially more color information than can possibly be displayed and as such, are wasteful of both memory and system resources.
Unfortunately, in order to accommodate the most general situations, conventional embedded image encoding and decoding systems use a 24 bit conversion methodology regardless of the ultimate display capability of the end user. By way of example, if, as shown in FIG. 1 illustrating a conventional image decoding system 100, an image producer 102 provides an 8-bit image 104 to an image filter 106 coupled to an image consumer, such as a display monitor 108. Typically, the image filter 106 filters the image 104 on a pixel by pixel basis to produce a 24 bit representation of the image regardless of the capability of the display monitor 106. By rendering a 24 bit image representation, the image decoder 100 is capable of handling even those situations where a 24-bit display monitor is available. However, this capability comes at the cost of slow performance and wasted resources for the most other applications for which a 24 bit display monitor is not used.
Therefore, what is desired is an efficient method and apparatus for intelligently decoding a compressed digital image based, in part, upon the display capability of the end user.
Broadly speaking, the invention relates to an improved method, apparatus and computer system for efficiently decoding a compressed digital image. The invention can be implemented in numerous ways, including as a method, a computer system, and an apparatus. Several embodiments of the invention are discussed below.
According to one aspect of the present invention, in an object based computer system, a computer implemented method for displaying a digital image on a display monitor coupled to the computer system is disclosed. After the format and output color model of a received digital image are determined, then the digital image is directly decoded using the output color model. The decoded image is then sent to the monitor for viewing.
In one embodiment of the invention, image is included in a web page requested by a web browser resident on the computer system.
In another embodiment of the invention, the image decoder is included in a browser that is resident in a set top box coupled to a television system having a display monitor. The set top box is arranged to receive documents from a host computer that includes a digital image. The image decoder receives the digital image, and based upon the display characteristics of the display monitor, decodes the digital image. In a preferred embodiment, the image decoder directly decodes the digital image which is then sent directly to the display monitor with no intermediate image decoding.